Patent Literature 1 describes an apparatus including an air chamber, and a discharge port communicating with the air chamber. The apparatus further includes an air cannon, a rod, and a cam. The air cannon discharges an air vortex by changing the volume of the air chamber. The rod is provided to the air cannon and is movable to an advanced position where the air chamber is reduced and a retracted position where the air chamber is expanded. The cam is attached to the rod with the center of rotation tilted relative to the rod, and moves the rod to the advanced position and the retracted position. The apparatus is configured such that the rod is moved instantaneously by rotation of the cam to cause the air in the air chamber to be injected from the discharge port to generate an air vortex ring.